The present invention relates to the separation of a flowback effluent stream and, in particular, to systems and methods for the real-time analysis of the composition of an input flowback effluent stream or one or more separated output effluent streams.
Flowback is the discharge of an effluent stream of mixed materials that is generated during a remedial operation directed, for example, toward well completion or fracture stimulation. The flowback effluent stream may contain one or more of water, liquid hydrocarbons, chemical additives, cuttings, abrasives, proppants, suspended solids, emulsions, and entrained gases. Disposal of this effluent stream may be difficult and costly, depending on the particular composition of the effluent stream, in light of environmental regulations and responsible corporate behavior. With the increased use of hydraulic fracturing to increase the productivity of certain reservoirs, future environmental regulatory requirements may require an accounting of the amount of chemicals introduced into a wellbore as well as the amount removed in an effluent stream in a hydraulic fracturing operation.
Most hydrocarbon-bearing reservoirs produce a mixture of oil and/or gas together with water, usually in the form of brine, and large amounts of dissolved minerals or precipitates, mostly common salts. In fact, in some oil wells, water and other by-products can amount to as much as eighty to ninety percent of the total production yield. This is particularly true during the later stages of production. Somewhere in the production process the produced mixture undergoes a separation process where the oil/gas is separated from the remaining components of the mixture and subsequently delivered to a refinery for treatment. The water and remaining components are usually removed from the hydrocarbons using one or more single phase or multi-phase separation devices. Generally, these devices operate to agglomerate and coalesce the produced hydrocarbons, thereby separating them from the water and other components of the produced mixture. Similar separation processes may be used to process a flowback effluent stream.
In some production and flowback cases, the separated water and other components are able to be pumped back into the ground, perhaps in some borehole neighboring the one from which it was removed. This process simply replaces a portion of the liquid removed from the reservoir, but also simultaneously serves to maintain required formation pressures for efficient production rates. In offshore applications, it is often desirable to discharge the produced water directly into the surrounding ocean, thereby eliminating the expense of pumping the fluid back downhole.
Before the water can be discharged into the ocean, however, or any other body of water (e.g., rivers, lakes, streams, etc. in other applications) it must first be rigorously tested to make sure that it does not contain any oil or other impurities that could damage the surrounding sea life. As environmental regulations increasingly become more stringent with respect to the disposal of produced water into the ocean, it becomes increasingly crucial to obtain accurate and timely analysis of the separated fluids to ensure compliance with the regulations.